Present FET (field effect transistor) circuits utilized as oscillators show relatively high output amplitude variations as a function of the operating frequency or output loading. If the amplitude of the oscillator output is too high, undesired distortion may result.
Various circuits are known for controlling the output of an FET oscillator. For example, U.S. Pat. No. 3,723,905 discloses an oscillator circuit, including a dual-gate MOS FET arranged in a Hartley oscillator configuration and operated to maintain the oscillator signal output level substantially constant over a wide frequency range.
Also, various circuits are known for controlling the output of junction transistors. For example, U.S. Pat. No. 3,596,207 discloses a voltage control oscillator (VCO), which is so designed that the output pulse width can be kept substantially constant, irrespective of any variation in the input control voltage.